And what's more, just like the Tardis they suddenly appear from nowhere.

But you won't be transported to any distant galaxies in this mysterious-looking stainless steel booth, just mightily relieved that you don't have to cross your legs and endure a bladder-bursting taxi ride home.

These are the latest loos to hit the street or, more accurately, pop up out of the street.

This hydraulic pop-up loo is completely concealed in the ground, but emerges between 9pm and 6am to answer the call of nature for revellers returning from pubs and clubs.

The loos are one option being explored by Wrexham County Council officers devising a "public conveniences strategy" for the town.

The Dutch-made Urilifts were first introduced into the UK 18 months ago by Reading Borough Council, and officers from Wrexham recently visited the city to make a closer inspection.

One reason why the Urilift is not used during the day is that it is completely open - there is only your back to protect your modesty.

But the Reading experience suggests the British, when confronted with the pop-up French pissoir, lose their sense of reserve and are quite happy to embrace the continental approach and "go" alfresco.

So much so that at the Urilift's official unveiling ceremony in Reading featuring the music of Strauss's Also Sprach Zarathustra, atmospheric smoke, fireworks and silver confetti an unscheduled visit was made by a man on his way out of a local pub.

As the assembled press looked on in astonishment "Belfast Rab", as he is known locally, made his way through the crowd and before anyone had a chance to stop him demonstrated that the Urilift was indeed fit for purpose.

Since then the two-metre high Urilift has enjoyed a period of near complete success in Reading with just one minor breakdown in 18 months.

At busy times revellers have been seen queuing to use it.

In London's West End, where the Urilifts have also been introduced, and Reading a new urban street language has grown up around it.

The only problem with Reading's and the West End's Urilifts, of course, is that they offer night-time relief for only half their cities' revellers.

The pop-up urinal comes in two versions - male and female. The Urilift is designed only for men, while women use the UriGienic, which offers complete privacy.

Since men are seen as responsible for most "street urination", local authorities have so far only been willing to opt for the male version.